Capacitor and method for making same

ABSTRACT

A system-on-chip (SOC) device comprises a first capacitor in a first region, a second capacitor in a second region, and may further comprise a third capacitor in a third region, and any additional number of capacitors in additional regions. The capacitors may be of different shapes and sizes. A region may comprise more than one capacitor. Each capacitor in a region has a top electrode, a bottom electrode, and a capacitor insulator. The top electrodes of all the capacitors are formed in a common process, while the bottom electrodes of all the capacitors are formed in a common process. The capacitor insulator may have different number of sub-layers, formed with different materials or different thickness. The capacitors may be formed in an inter-layer dielectric layer or in an inter-metal dielectric layer. The regions may be a mixed signal region, an analog region, a radio frequency region, a dynamic random access memory region, and so forth.

PRIORITY CLAIM AND CROSS-REFERENCE

This application is a continuation of U.S. patent application Ser. No. 15/412,583, filed Jan. 23, 2017, and entitled “Capacitor and Method for Making Same,” which is a continuation of U.S. application Ser. No. 14/103,307, filed Dec. 11, 2013, entitled, “Capacitor and Method for Making Same,” now U.S. Pat. No. 9,553,095 issued Jan. 24, 2017, which is a divisional of U.S. application Ser. No. 13/267,424, filed Oct. 6, 2011, entitled, “Capacitor and Method for Making Same,” now U.S. Pat. No. 8,617,949 issued Dec. 31, 2013, which is a continuation-in-part of U.S. patent application Ser. No. 12/618,021, filed on Nov. 13, 2009, entitled “Dual-Dielectric MIM Capacitors for System-on-Chip Applications,” now U.S. Pat. No. 8,143,699 issued Mar. 27, 2012, which application claims the benefit of U.S. Provisional Application No. 61/527,669 filed on Aug. 26, 2011, entitled “Capacitor and Method for Making Same,” which applications are hereby incorporated herein by reference.

BACKGROUND

Many kinds of capacitors such as metal-oxide-semiconductor (MOS) capacitors, PN junction capacitors, polysilicon-insulator-polysilicon (PIP) capacitors, and metal-insulator-metal (MIM) capacitors are used in semiconductor devices. In particular, the MIM capacitor offers reduced electrode resistance with wide ranges of applications.

MIM capacitors have been widely used in functional circuits such as mixed signal circuits, analog circuits, radio frequency (RF) circuits, dynamic random access memory (DRAM), embedded DRAM, and logic operation circuits. In system-on-chip applications, different capacitors for different functional circuits have to be integrated on a same chip to serve different purposes. For example, in mixed signal circuits, capacitors are used as decoupling capacitors and high-frequency noise filters. For DRAM and embedded DRAM circuits, capacitors are used for memory storage; while for RF circuits, capacitors are used in oscillators and phase-shift networks for coupling and/or bypassing purposes. For microprocessors, capacitors are used for decoupling. The traditional way to combine these capacitors on a same chip is to fabricate them in different metal layers.

With the capacitors having different functions formed in different metal layers, the capacitors may work under different operation voltages. For example, when used as decoupling capacitors, the capacitors need to be able to sustain high voltages. Therefore, the capacitor insulators need to be thick. In DRAMs, on the other hand, the operation voltage is low, and the capacitors need to be small in order to increase the DRAM cell density. Therefore, the capacitor insulators need to be thin.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates an embodiment of four regions where one capacitor is located within one region for three regions while the top electrode and the bottom electrode of the capacitors are formed in a common process;

FIG. 2 illustrates an embodiment wherein one of the regions may have multiple capacitors with different capacitor insulators;

FIGS. 3a-5f illustrate embodiments of processes of fabricating three capacitors in three regions with different numbers of sub-layers; and

FIG. 6 illustrates two regions each with a capacitor formed in an IMD layer rather than ILD layer.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the embodiments of the present disclosure are discussed in detail below. It should be appreciated, however, that the embodiments of the present disclosure provide many applicable concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention.

It is realized that for a system-on-chip (SoC) application, different functional capacitors may be needed in different functional regions (circuits), such as a mixed signal region, an analog region, a radio frequency (RF) region, a dynamic random access memory (DRAM) region, a logic region, and a static random access memory (SRAM) region. To reduce the manufacturing cost and to reduce the process complexity, all these capacitors may be manufactured in a common process, e.g., substantially simultaneously, in a substantially same level, for example, in a same metal layer. Accordingly, all of the insulators in the capacitors have a same thickness and are formed of a same material. However, this results in a dilemma. For example, in order to accommodate the high voltage in the mixed signal regions, the analog regions, or the like, the decoupling capacitors need to have thick capacitor insulators. However, thicker capacitor insulators result in smaller capacitance per unit chip-area. As a result, DRAM capacitors, which may have high densities, are forced to occupy greater chip areas. Conversely, to suit the high-density requirement of the DRAM capacitors, the capacitor insulators need to be thin. This, however, means that the reliability of the capacitors in the mixed signal region and the analog region may be sacrificed due to the reduced insulator thickness.

To solve the above-discussed dilemma, a novel integration scheme for integrating different functional metal-insulator-metal (MIM) capacitors on a same SoC chip and the corresponding structures is provided. A MIM capacitor may be a capacitor having a stacked structure, for example, including a bottom electrode, a top electrode, and an insulator therebetween. The intermediate stages of manufacturing exemplary embodiments are also illustrated. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements.

FIG. 1 illustrates an exemplary embodiment. Semiconductor chip 10, which has system-on-chip (SoC) applications built therein, is provided. Chip 10 comprises region 100, region 200, region 300, and region 400. In an embodiment, region 100, 200, and 300 may be a mixed signal region, an analog region, a radio frequency (RF) region, respectively, or a combined region including more than one of these regions. Region 400 may be a logic region having core (logic) devices, a static random access memory (SRAM) region, or a combined region including both logic and SRAM circuits. Chip 10 includes substrate 12 that expands through regions 100, 200, 300, and 400. Substrate 12 may be a silicon substrate, or a substrate comprising other semiconductor materials, such as group III, group IV, and/or ground V elements. Layers 15 and 17 are inter-layer dielectrics (ILD).

In region 100, capacitor 102 is formed. Shallow trench isolation (STI) region 104 is formed in substrate 12 and vertically overlaps capacitor 102, wherein the area of STI region 104 is preferably greater than, although it may also be equal to or slightly less than, the area of capacitor 102. In an embodiment, STI region 104 fully vertically overlaps all of the overlying capacitor 102, and may further expand beyond the edges of capacitor 102 in lateral directions (the directions parallel to the surface of substrate 12). In other embodiments, STI region 104 has an area greater than about 90 percent of the area of capacitor 102. In an embodiment, capacitor 102 is formed in ILD 17, which is lower than the bottom metallization layer (commonly known as M1). Please note that ILD 17 may be the dielectric layer covering gates 208, 308, and 408. In this case, capacitor 102 is connected to contact plugs 106, which may be formed of tungsten. In region 100, polysilicon strip 108 is formed. Silicide 110 is formed on polysilicon strip 108 by a silicidation process. Contact etch stop layer (CESL) 112 is formed on silicide 110. Polysilicon strip 108, silicide 110, and CESL 112 may be formed in a common process, and hence comprise the same materials as gates 208, 308, and 408, gate silicides and source (or drain) silicides, and the CESLs in regions 200, 300, and 400, respectively. Similarly, the illustrated contact plugs 106, 206, 306, and 406 may be formed in a common process using a same conductive material. It is noted that capacitor 102 may have its bottom electrode 122 interconnected through contact plugs 106 and silicide 110, and its top electrode 124 interconnected by itself. As a result, capacitor 102 may act as a single capacitor. Throughout the description, bottom electrode 122 and other bottom electrodes and top electrodes may be formed of titanium nitride (TiN) or combinations of titanium (Ti) with titanium nitride, tantalum nitride (TaN), tungsten (W), tungsten nitride (WN), ruthenium (Ru), iridium (Jr), and platinum (Pt). Generally, low-resistivity materials may be used.

Capacitor 202 is formed in IDL 17 of region 200, and may be used as the storage capacitor of a DRAM cell or provide other functions. The bottom electrodes 122 within region 100 and 222 within region 200 may be formed in a common process, and hence are formed of a same conductive material, have a same thickness, and essentially at the same level. Further, the top electrodes 124 within region 100 and 224 within region 200 are formed in a common process, and hence are formed of a same conductive material, have a same thickness, and essentially at the same level. Capacitors 102 and 202 may comprise vertical portions (sidewall portions) and horizontal portions (bottom portions), and hence are also referred to as three-dimensional (3D) capacitors, since capacitors 102 and 202 not only extend in the direction parallel to the top surface of substrate 12, but also in a vertical direction perpendicular to the top surface of substrate 12. This advantageously increases the capacitance per unit chip-area.

Capacitor 302 is further formed in IDL 17 of region 300, and may be used as the storage capacitor of a DRAM cell or perform other functions. Similarly, the bottom electrodes 122, 222, and 322 may be formed in a common process, and hence are formed of a same conductive material, have a same thickness, and essentially at the same level. Further, the top electrodes 124, 224, and 324 are formed in a common process, and hence are formed of a same conductive material, have a same thickness, and essentially at the same level. Capacitors 102, 202, and 302 may be 3D capacitors, since capacitors 102, 202, and 302 not only extend in the direction parallel to the top surface of substrate 12, but also in a vertical direction perpendicular to the top surface of substrate 12. This advantageously increases the capacitance per unit chip-area.

Furthermore, there may be no capacitors in region 400. Region 400 may be a logic region having core (logic) devices, a static random access memory (SRAM) region, or a combined region including both logic and SRAM circuits.

In an illustrative embodiment, as shown in FIG. 1, capacitor 102 may comprise a capacitor insulator 130 between, and contacting, bottom electrode 122 and top electrode 124. Unless specified otherwise, insulator 130 and other insulators discussed in the specification may include silicon dioxide (SiO₂), silicon nitride (Si₃N₄), aluminum oxide (Al₂O₃), hafnium silicates (HfSiON), tantalum oxide (Ta₂O₅), zirconium oxide (ZrO₂), hafnium oxide (HfO₂), titanium oxide (TiO₂), barium strontium titanate oxide (BST), strontium titanate oxide (STO), and combinations thereof. Capacitor 202 includes capacitor insulator 230 between, and contacting, respective bottom electrode 222 and top electrode 224. Similarly, capacitor 302 includes capacitor insulator 330 between, and contacting, respective bottom electrode 322 and top electrode 324.

The capacitor insulator 130 includes capacitor dielectric layer 130 ₁ and layer 130 ₂, wherein layer 130 ₁ is formed in a common process as, and hence comprises a same material, and has a same thickness, as capacitor insulator 230 and 330. Capacitors 202 and 302 however, do not include any layer that is formed in a common process with capacitor dielectric layer 130 ₂. Accordingly, capacitor 102, with two dielectric layers stacked together, has a greater breakdown voltage, and hence improved reliability. This is particularly desirable since the voltages applied to capacitor 102 are often high, for example, when used as decoupling capacitors with one of the bottom electrode 122 and top electrode 124 connected to voltage VDD, and the other one connected to voltage VSS. In FIG. 1, dotted lines 134 illustrate a contact connecting top electrode 124 to a M1 metal line. In this case, the M1 metal line may be a VDD power line or a VSS power line.

In some other embodiments, the layer 130 ₂ instead of the layer 130 ₁ is formed in a common process as, and hence comprises a same material, and has a same thickness, as capacitor insulator 230 and 330. In either case, capacitors 202 and 302, have only one dielectric layer, and hence can endure lower operation voltage than capacitor 102, and therefore may be used in low voltage applications. With thin capacitor insulators, capacitors 202 and 302 have a high capacitance per unit chip-area. This is desirable since a DRAM array may include many storage capacitors, and hence the increased capacitance per unit chip-area is advantageous for increasing the density of the DRAM array.

Capacitors 202 and 302 are only shown for illustration purposes and are not limiting. Other embodiments may comprise other forms of capacitors 202 and 302. For example, capacitor 302 may have two dielectric layers formed at the same time as the dielectric layer 130 ₁ and layer 130 ₂, while capacitor 202 has only one dielectric layer. Capacitors 202 and 302 may both have two dielectric layers as the dielectric layer 130 ₁ and layer 130 ₂ formed in capacitor 102.

The number of regions 100, 200, 300, and 400, and the capacitors 102, 202, and 302 are only for illustrative purposes and are not limiting. For some other embodiments, there may be two regions 100 and 200 comprising two capacitors 102 and 202 in addition to the region 400, without the region 300 and the capacitor 302 within. For some other embodiments, there may be more than three regions 100, 200, 300 that comprise capacitors 102, 202, and 302. For example, there may be four regions with a MIM capacitor or more within each region, while each region may be a mixed signal region, an analog region, a radio frequency (RF) region, or a combined region including more than one of these regions.

In FIG. 1, each region 100, 200, and 300 has only one capacitor. In other embodiments, there may be more than one capacitor within a region. FIG. 2 illustrates one exemplary region, such as region 200 in FIG. 1. The capacitors shown in region 200 are only for illustration purposes and are not limiting. Capacitors in other regions such as region 100, 300 can have similar variations as shown for region 200.

In FIG. 2, there are two non-connected capacitors 202-1 and 202-2 formed in IDL 17 of region 200, which may be used as the storage capacitors of DRAM cells or perform other functions. The capacitor 202-1 has two openings 202-1-o1 and 202-1-o2, while the capacitor 202-2 has only one opening 202-2-o1. The number of openings is only for illustration purposes and is not limiting. There may be more than two openings. The size of the two openings may be different. For example, the two openings 202-1-o1 and 202-1-o2 have different sizes.

In addition, FIG. 2 illustrates an embodiment, wherein the capacitor 202-1 and 202-2 have only one layer of capacitor insulator 230-1 and 230-2 formed respectively. Moreover, the capacitor insulator 230-1 and 230-2 may either be formed of a different material, or have a different thickness, from each other, and may or may not be different from other capacitor insulators 130 in region 100 and 330 in region 300 of FIG. 1. In embodiments of the disclosure, capacitor insulators are referred to as being different from each other if they comprise at least one different material, or have a different thickness in at least one of the sub layers. In other words, the capacitor insulators are different unless they have a same thickness and are formed of a same material.

With the capacitor insulators in regions being different from each other, the insulators for each type of capacitor may be customized as needed, and hence the chip area occupied by the capacitors may be minimized without sacrificing the reliability (e.g., the endurance to the voltages) of the capacitors. This is particularly advantageous since both DRAM capacitors (for their big number) and decoupling capacitors may occupy large chip areas, thus being able to customize the insulators of capacitors is important.

In addition, besides the above-discussed dual-dielectric or single-dielectric capacitors, triple-dielectric or other multi-capacitor-insulator capacitors may be formed with even more capacitor insulator layers. Different combinations of capacitor insulator layers may be made to minimize the process steps. However, at least the formation processes of the top electrodes and the bottom electrodes of different capacitors may be combined. Furthermore, capacitors with other shapes and forms may be formed in regions 100, 200, and 300, or other number of regions.

FIG. 3(f) illustrates exemplary MIM capacitors 102, 202, and 302 formed in region 100, 200, and 300 respectively by a process shown in FIGS. 3(a)-3(f). The capacitors may comprise a bottom electrode 122, 222, and 322 which are formed in a common process, and top electrode 124, 224, and 324 which are formed in a common process. A bottom electrode pick-up 121, 221, and 321 are formed and connected to the bottom electrode 122, 222, and 322 respectively, to connect to a metal layer down or the gates of transistors. A top electrode pick-up may be formed as well (not shown). The capacitors 102, 202, and 302 may be of cylindrical shape and FIGS. 3(a)-3(f) show only the cross-section view. They may be other shapes such as a concave shape. FIG. 3(f) is only for illustrative purposes and is not limiting. For example, there may be more than one capacitor so formed by the illustrative process in each region.

The capacitors 102, 202, and 302 in FIG. 3(f) may be fabricated by an illustrative process shown in FIGS. 3(a)-(f). In FIG. 3(a), the illustrative process starts with forming a metal contact 121, 221, and 321, sometimes also referred to as a bottom electrode pick-up. An ILD 17 is formed by depositing dielectric materials such as USG oxide film. A plurality of openings 125, 225, and 325 are formed within the layers 17 on top of the metal contacts 121, 221, and 321 respectively by photolithography. The openings 125, 225, and 325 are in direct contact with the metal contacts. FIG. 3(a) is a cross-section view, and the openings 125, 225, and 325 may be shaped as a cup (i.e., openings may have a substantially circular shape when seen from above). The number, the position, the size, the width, and the shape of the openings 125, 225, and 325 are only for illustrative purposes only, but are not limiting.

FIG. 3(a) further illustrates bottom electrode material 122, 222, and 322 are deposited at the bottom and along the side wall of the openings 125, 225, and 325, respectively. The material deposited at the bottom of the openings 125, 225, and 325 is in contact with the metal contacts forming an electrical contact path. The material may be conductive materials such as TaN or TiN, or silicided metal nitride such as TaSiN, TiSiN, and WSiN. There may be multiple sub-layers (not shown) comprising the conductive materials. A chemical mechanical planarization (CMP) is used to remove any extra bottom electrode material to form the bottom electrode, which are all formed in a common process.

FIG. 3(a) further illustrates a layer of capacitor dielectric 130-1 is deposited on top of the bottom electrode 122, 222, and 322 across the three regions 100, 200, and 300, respectively, at the bottom and along the side wall of the openings 125, 225, and 325, and on top of the related surface by means including ALD, LPCVD, PECVD, and ALCVD. The material may include any capacitor dielectric such as SiO₂, metal nitrides, such as silicon nitride (e.g., Si₃N₄) or high dielectric constant (high-k) materials such as TiO₂, Ta₂O₅, ZrO₂, including rare earth oxides such as Y₂O₃, La₂O₅, HfO₂, and their aluminates and silicates.

In FIG. 3(b), a photoresist protective coating 127 is applied over the dielectric 130-1 in regions 100 and 200, but not in region 300. The protective coating 127 covers and protects all or a part of the capacitor dielectric 130-1 in region 100 and 200, so that and the same layer 130-1 in region 300 may be removed during a subsequent etching process, as shown in FIG. 3(b).

FIG. 3(c) further illustrates a second sub-layer of capacitor dielectric 130-2 is deposited on top of the first sub-layer 130-1 across the three regions 100, 200, and 300, respectively, at the bottom and along the side wall of the openings 125, 225, and 325, and on top of the surface. Subsequently, as shown in FIG. 3(d), a photoresist protective coating 128 is applied over the dielectric 130-2 in regions 100 and 300, but not in region 200. The protective coating 128 covers and protects all or a part of the capacitor dielectric 130-1 and/or 130-2 in region 100 and 300, so that and the same layer 130-2 and 130-1 in region 200 can be removed during a subsequent etching process, as shown in FIG. 3(d).

FIG. 3(e) further illustrates a third sub-layer of capacitor dielectric 130-3 is deposited across the regions 100, 200, and 300, respectively, on top of the sub-layer 130-2, and at the bottom and along the side wall of the opening 225 where no dielectric layer material remaining since it is removed in step 3(d). As the last step shown in FIG. 3(f), top electrode 124, 224, and 324 are formed in a common process in regions 100, 200, 300, on top of the sub-layer 130-3.

As the result of the above process, capacitor 102 in region 100 has three sub-layers 130-1, 130-2, and 130-3 to form the capacitor insulator, while capacitor 202 in region 200 has only one sub-layer 130-3 to form the capacitor insulator, and capacitor 302 in region 300 has two sub-layers 130-3 and 130-2 to form the capacitor insulator. The three capacitors formed in three regions have different number of sub-layers of capacitor insulator, leading to different capacitance for different functions. Moreover, the bottom electrode and the top electrode of the capacitors are formed in a common process. The number of sub-layers and the number of capacitors in each region are only shown for illustrative purposes and are not limiting.

The process shown in FIGS. 3(a)-3(f) can be similarly applied to other shapes of capacitors. FIGS. 4(a)-4(f) show how to form bar-type capacitors in each region using the same process. FIGS. 5(a)-5(f) show how to form planar type capacitors in each region using the same process. It is possible to apply the same process to form mixed shaped capacitors in different regions. For example, a cylinder type capacitor may be formed in region 100, a bar type capacitor may be formed in region 200, and a planar type or other type of capacitor may be formed in region 300, using the same process. The embodiments shown are only for illustrative purposes and are not limiting.

FIG. 4(f) illustrates exemplary MIM capacitors 102, 202, and 302 formed in region 100, 200, and 300 respectively by a process shown in FIGS. 4(a)-(f). The capacitors may comprise a bottom electrode 122, 222, and 322 which are formed in a common process and top electrode 124, 224, and 324 which are formed in a common process. A bottom electrode pick-up 121, 221, and 321 are formed and connected to the bottom electrode 122, 222, and 322 respectively, to connect to a metal layer down or the gates of transistors. A top electrode pick-up may be formed as well (not shown). The capacitors 102, 202, and 302 may be of bar shape and FIGS. 4(a)-4(f) show only the cross-section view. FIG. 4(f) is only for illustrative purposes and is not limiting. For example, there may be more than one capacitor so formed by the illustrative process in each region.

The capacitors 102, 202, and 302 in FIG. 4(f) may be fabricated by an illustrative process shown in FIGS. 4(a)-4(f). In FIG. 4(a), the illustrative process starts with forming a metal contact 121, 221, and 321, sometimes also referred to as a bottom electrode pick-up. On top of the metal contacts, a bar shaped bottom electrode 122, 222, and 322 may be formed as shown in FIG. 4(a), in contact with the metal contacts forming an electrical contact path. The material may be conductive materials such as TaN or TiN, or silicided metal nitride such as TaSiN, TiSiN, and WSiN. FIG. 4(a) is a cross-section view, and the bars 122, 222, and 322 may be shaped as a square (i.e., bars may have a substantially square shape when seen from above). The number, the position, the size, and the width of the bars 122, 222, and 322 are only for illustrative purposes only, but are not limiting.

FIG. 4(a) further illustrates a layer of capacitor dielectric 130-1 is deposited on top of the bottom electrode 122, 222, and 322 across the three regions 100, 200, and 300, respectively, by means including ALD, LPCVD, PECVD, and ALCVD. The material may include any capacitor dielectric such as SiO₂, metal nitrides, such as silicon nitride (e.g., Si₃N₄) or high dielectric constant (high-k) materials such as TiO₂, Ta₂O₅, ZrO₂, including rare earth oxides such as Y₂O₃, La₂O₅, HfO₂, and their aluminates and silicates.

In FIG. 4(b), a photoresist protective coating 127 is applied over the dielectric 130-1 in regions 100 and 200, but not in region 300. The protective coating 127 covers and protects all or a part of the capacitor dielectric 130-1 in region 100 and 200, so that and the same layer 130-1 in region 300 can be removed during a subsequent etching process, as shown in FIG. 3(b).

FIG. 4(c) further illustrates a second sub-layer of capacitor dielectric 130-2 is deposited across the three regions 100, 200, and 300, respectively, on top of the first sub-layer 130-1, or on top of the surface of the bar. Subsequently, as shown in FIG. 4(d), a photoresist protective coating 128 is applied over the dielectric 130-2 in regions 100 and 300, but not in region 200. The protective coating 128 covers and protects all or a part of the capacitor dielectric 130-1 in region 100 and 300, so that and the same layer 130-2 and 130-1 in region 200 can be removed during a subsequent etching process, as shown in FIG. 4(d).

FIG. 4(e) further illustrates a third sub-layer of capacitor dielectric 130-3 is deposited across the regions 100 and 300, respectively, on top of the sub-layer 130-2, and at the top of the bar 222 in region 200 where no dielectric layer material remaining since it is removed in step 4(d). As the last step shown in FIG. 4(f), top electrode 124, 224, and 324 which are formed in a common process in regions 100, 200, 300, on top of the sub-layer 130-3.

As the result of the above process, capacitor 102 in region 100 has three sub-layers 130-1, 130-2, and 130-3 to form the capacitor insulator, while capacitor 202 in region 200 has only one sub-layer 130-3 to form the capacitor insulator, and capacitor 302 in region 300 has two sub-layers 130-3 and 130-2 to form the capacitor insulator. The three capacitors formed in three regions have different number of sub-layers of capacitor insulator, leading to different capacitance for different functions. Moreover, the bottom electrode and the top electrode of the capacitors are formed in a common process. The number of sub-layers and the number of capacitors in each region are only shown for illustrative purposes and are not limiting.

FIG. 5(f) illustrates exemplary MIM capacitors 102, 202, and 302 formed in region 100, 200, and 300 respectively by a process shown in FIGS. 5(a)-5(f). The capacitors may comprise a bottom electrode 122, 222, and 322 which are formed in a common process and top electrode 124, 224, and 324 which are formed in a common process. A bottom electrode pick-up 121, 221, and 321 are formed and connected to the bottom electrode 122, 222, and 322 respectively, to connect to a metal layer down or the gates of transistors. A top electrode pick-up may be formed as well (not shown). The capacitors 102, 202, and 302 may be of planar shape and FIGS. 5(a)-5(f) show only the cross-section view. FIG. 5(f) is only for illustrative purposes and is not limiting. For example, there may be more than one capacitor so formed by the illustrative process in each region.

The capacitors 102, 202, and 302 in FIG. 5(f) may be fabricated by an illustrative process shown in FIGS. 5(a)-(f). In FIG. 5(a), the illustrative process starts with forming a metal contact 121, 221, and 321, sometimes also referred to as a bottom electrode pick-up. Bottom electrode material 122, 222, and 322 are deposited in contact with the metal contacts forming an electrical contact path. The material may be conductive materials such as TaN or TiN, or silicided metal nitride such as TaSiN, TiSiN, and WSiN. There may be multiple sub-layers (not shown) comprising the conductive materials. The extra so formed bottom electrode material may be removed by a chemical mechanical planarization (CMP) to form the bottom electrode. FIG. 5(a) is a cross-section view, and the bottom electrode 122, 222, and 322 may be shaped as a square (i.e., the area above the metal contacts may have a substantially square shape when seen from above). The number, the position, the size, and the width are only for illustrative purposes only, but are not limiting.

FIG. 5(a) further illustrates a layer of capacitor dielectric 130-1 is deposited on top of the bottom electrode 122, 222, and 322 across the three regions 100, 200, and 300, respectively, by means including ALD, LPCVD, PECVD, and ALCVD. The material may include any capacitor dielectric such as SiO₂, metal nitrides, such as silicon nitride (e.g., Si₃N₄) or high dielectric constant (high-k) materials such as TiO₂, Ta₂O₅, ZrO₂, including rare earth oxides such as Y₂O₃, La₂O₅, HfO₂, and their aluminates and silicates.

In FIG. 5(b), a photoresist protective coating 127 is applied over the dielectric 130-1 in regions 100 and 200, but not in region 300. The protective coating 127 covers and protects all or a part of the capacitor dielectric 130-1 in region 100 and 200, so that and the same layer 130-1 in region 300 can be removed during a subsequent etching process, as shown in FIG. 5(b).

FIG. 5(c) further illustrates a second sub-layer of capacitor dielectric 130-2 is deposited across the three regions 100, 200, and 300, respectively, on top of the first sub-layer 130-1, or on top of the surface of 322. Subsequently, as shown in FIG. 5(d), a photoresist protective coating 128 is applied over the dielectric 130-2 in regions 100 and 300, but not in region 200. The protective coating 128 covers and protects all or a part of the capacitor dielectric 130-1 in region 100 and 300, so that and the same layer 130-2 and 130-1 in region 200 can be removed during a subsequent etching process, as shown in FIG. 5(d).

FIG. 5(e) further illustrates a third sub-layer of capacitor dielectric 130-3 is deposited on top of the sub-layer 130-2 across the regions 100 and 300, respectively, and at the top of 222 where no dielectric layer material remaining since it is removed in step shown in FIG. 5(d). As the last step shown in FIG. 5(f), top electrode 124, 224, and 324 which are formed in a common process in regions 100, 200, 300, on top of the sub-layer 130-3.

As the result of the above process, capacitor 102 in region 100 has three sub-layers 130-1, 130-2, and 130-3 to form the capacitor insulator, while capacitor 202 in region 200 has only one sub-layer 130-3 to form the capacitor insulator, and capacitor 302 in region 300 has two sub-layers 130-3 and 130-2 to form the capacitor insulator. The three capacitors formed in three regions have different number of sub-layers of capacitor insulator, leading to different capacitance for different functions. Moreover, the bottom electrode and the top electrode of the capacitors are formed in a common process. The number of sub-layers and the number of capacitors in each region are only shown for illustrative purposes and are not limiting.

In FIG. 6, in an alternative embodiment, capacitors 202 in region 200 and 302 in region 300 are formed in layers higher than ILD 17, for example, in any of the dielectric layers known as inter-metal dielectrics (IMDs) 19, which are commonly known in the art as being the dielectric layers for forming metal lines and vias therein. Further, the IMDs are higher than metallization layer M1. Only two regions 200 and 300 are shown. Other number of regions and capacitors are possibly formed in the IMD layer 19.

In FIG. 6, capacitor 202 is formed in region 200 in IMD layer 19, which is above the third metal layer M3 and below the fourth metal layer M4. The metal layers M1, M2, M3, and M4 are connected by vias 106. The number of metal layers and IMD layers, and the number of vias are only shown for illustrative purposes and is not limiting. Similarly, bottom electrode 222 of capacitor 202 and bottom electrode 322 of capacitor 302 are formed in a common process, and hence are formed of a same conductive material. Further, top electrodes 224 and 324 are formed in a common process, and hence are formed of a same conductive material. Capacitor insulator 230 is in between, and contacting, bottom electrode 222 and top electrode 224. Capacitor insulator 330 is in between, and contacting, bottom electrode 322 and top electrode 324. Insulator 230 and 330 may contain multiple sub-layers, made of different material of different thickness.

The embodiments of the present invention have several advantageous features. By integrating capacitors in different functional regions, the process steps and complexity for forming multiple functional capacitors are reduced. The reliability and chip-area usage of the capacitors, on the other hand, are improved.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, and composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. In addition, each claim constitutes a separate embodiment, and the combination of various claims and embodiments are within the scope of the invention. 

What is claimed is:
 1. An integrated circuit device comprising: a first dielectric layer; a second dielectric layer; a third dielectric layer; a conductive bottom contact comprising a planar top surface, wherein the planar top surface comprises a first portion and second portions; a first bottom electrode over and contacting a first portion of the planar top surface of the conductive bottom contact; a first capacitor insulator comprising a portion from each of the first, the second, and the third dielectric layers, wherein the first bottom electrode, the first capacitor insulator, and the first top electrode form portions of a first capacitor, and the first capacitor insulator comprising: a U-shaped portion contacting a top surface and sidewalls of the first bottom electrode; and horizontal portions contacting the second portions of the planar top surface of the conductive bottom contact, wherein in the first capacitor insulator, the second dielectric layer is over the first dielectric layer, and the third dielectric layer is over the second dielectric layer; and a first top electrode over and contacting the first capacitor insulator; a second bottom electrode and a second top electrode forming portions of a second capacitor, wherein a second capacitor insulator of the second capacitor comprises a portion of the third dielectric layer, and is free from portions from the first dielectric layer and the second dielectric layer; and a third bottom electrode and a third top electrode forming portions of a third capacitor, wherein a third capacitor insulator of the third capacitor comprises portions of the second and the third dielectric layers, and is free from portions from the first dielectric layer.
 2. The integrated circuit device of claim 1, wherein the first bottom electrode has a rectangular cross-sectional view shape.
 3. The integrated circuit device of claim 1, wherein the conductive bottom contact and the first bottom electrode form a distinguishable interface.
 4. The integrated circuit device of claim 1, wherein the U-shaped portion comprises sub-layers formed of different materials, with each of the sub-layers forming a U-shape.
 5. The integrated circuit device of claim 1, wherein the portions of the first, the second, and the third dielectric layers in the first capacitor form stacked layers, and a top surface and a bottom surface of the stacked layers are in contact with the first top electrode and the first bottom electrode, respectively.
 6. The integrated circuit device of claim 1, wherein the second bottom electrode and the second top electrode are both in physical contact with the portion of the first dielectric layer in the second capacitor insulator.
 7. The integrated circuit device of claim 1, wherein portions of the first and the second dielectric layers in the third capacitor insulator form stacked layers, and a top surface and a bottom of the stacked layers are in contact with the third top electrode and the third bottom electrode, respectively.
 8. An integrated circuit device comprising: a first dielectric layer; a second dielectric layer over the first dielectric layer; a third dielectric layer over the second dielectric layer; a first capacitor comprising: a first bottom electrode; a first top electrode; and a first capacitor insulator between the first bottom electrode and the first top electrode, wherein the first capacitor insulator comprises a portion from each of the first, the second, and the third dielectric layers, and the first capacitor insulator comprises a U-shaped portion, and an entirety of a space in the U-shaped portion is filled by a portion of the first bottom electrode; a second capacitor comprising: a second bottom electrode and a second top electrode; and a second capacitor insulator between the second bottom electrode and the second top electrode, wherein the second capacitor insulator comprises a portion of the third dielectric layer, and is free from portions from the first dielectric layer and the second dielectric layer; and a third capacitor comprising: a third bottom electrode and a third top electrode; and a third capacitor insulator between the third bottom electrode and the third top electrode, wherein the third capacitor insulator comprises portions of the second and the third dielectric layers, and is free from portions from the first dielectric layer.
 9. The integrated circuit device of claim 8, wherein the first capacitor insulator and the second capacitor insulator have different thicknesses.
 10. The integrated circuit device of claim 8 further comprising a conductive bottom contact underlying and contacting the first bottom electrode, wherein the first capacitor insulator further extends on a top surface of the conductive bottom contact.
 11. The integrated circuit device of claim 10, wherein the conductive bottom contact laterally extends beyond opposite edges of the first bottom electrode.
 12. The integrated circuit device of claim 8, wherein the first dielectric layer, the second dielectric layer, and the third dielectric layer are formed of different materials.
 13. An integrated circuit device comprising: a first capacitor comprising: a conductive bottom contact comprising a top surface, wherein the top surface comprises a first portion, a second portion, and a third portion, and wherein the second portion and the third portion are on opposing sides of, and joining with, the first portion; a bottom electrode over and contacting the first portion of the top surface of the conductive bottom contact, wherein the bottom electrode has a substantially rectangular shape in a cross-sectional view of the first capacitor; a capacitor insulator, wherein the capacitor insulator is in physical contact with the bottom electrode, and is in physical contact with both of the second portion and the third portion of the top surface of the conductive bottom contact; and a top electrode over and contacting the capacitor insulator.
 14. The integrated circuit device of claim 13, wherein the capacitor insulator comprises a plurality of sub-layers, wherein each of the sub-layers extends on the bottom electrode and the second portions of the top surface of the conductive bottom contact.
 15. The integrated circuit device of claim 14, wherein the plurality of sub-layers are formed of different materials.
 16. The integrated circuit device of claim 14, wherein the plurality of sub-layers comprise three sub-layers.
 17. The integrated circuit device of claim 13, wherein the capacitor insulator forms a U-shape, and in a cross-sectional view of the first capacitor, an entire inner space defined by the U-shape is filled by the bottom electrode.
 18. The integrated circuit device of claim 13, wherein the top electrode contacts the capacitor insulator, and the conductive bottom contact extends laterally beyond edges of the top electrode.
 19. The integrated circuit device of claim 13, wherein the conductive bottom contact extends laterally beyond edges of the bottom electrode, and the bottom electrode extends laterally beyond edges of the top electrode.
 20. The integrated circuit device of claim 13, wherein the capacitor insulator of the first capacitor comprises first portions of a first dielectric layer, a second dielectric layer, and a third dielectric layer, wherein in the first capacitor, the second dielectric layer is over the first dielectric layer, and the third dielectric layer is over the second dielectric layer, and the integrated circuit device further comprises: a second capacitor, wherein a second capacitor insulator of the second capacitor is a single-layer insulator comprising a second portion of the third dielectric layer; and a third capacitor, wherein a third capacitor insulator of the second capacitor is a double-layer insulator comprising a second portion of the second dielectric layer, and a third portion of the third dielectric layer. 